Power transmission



June 13, 1944.

F. T. HARRINGTON ET 11u.l

POWER TRANSMISSION Filed Sept. 23. 1940 FIG ' INVENTORS FERRIS w m m T.A

Patented June 13, 1944 UNITED STATES PATENT OFFICE POWER TRANSMISSIONFerris T. Harrington and James Robinson, De-

troit, Mich., assignors to Vickers Incorporated, Detroit, Mich., acorporation of Michigan Appueenep september 23, 1940, serial Ne. 351,396

41.1 Claims.

This invention relates to power transmissions,

particularly to those of the type comprising two availableat the supplyreel to operate the takel up reel.

It is also an object of the present invention to provide an improvedmeans for absorbing power generated at the supply reel independently ofwhether the strip material to be treated is later rewound on a reel oris utilized in the flat condition.

versely 'varying torque and speed is involved.

vWhere strip material is wound in a coil, one

layer on top of another, the problem of driving the reel so as tomaintain constant linear speed or constant tension in the strip as it iswound or unwound from the reel presents certain dimculties due to thenecessity of varying both the torque on the reel shaft and the speed ofthe reel shaft as the diameter of the reel changes.

In the handling of strip material as. for example, 'sheet metal, paper,cloth, and similar materials, it is frequently desirableto feed thestrip into a treating machine of one sort or anotherv from a supply reeland to again rewind the same strip into a coil by a take-up reel locatedat the output side of the treating machine. In such machines asheretofore constructed the apparatus provided for driving the take-upreel and the supply reel have been constructed as separate drivesentirely independent of one another. In any drive of this character thetake-up reel requires positive work to be performed on it while thesupply reel performs work as the strip material is unwound from thecoil; If the tension in the strip as it leaves the supply reel and as itapproaches the take-up reel is the same and if the reel core diametersare the same, it will be Further objects and advantages of the presentinvention will be apparent from the following de scription, referencebeing had to the accompanying drawing wherein a preferred form of thepresent invention is clearly shown.

In the drawing:

Figure 1 is a diagrammatic view of a hydraulic power transmission systemincorporating a pre-l ferred form of the present invention.

Figure 2 is a fragmentary sectional view of part of the mechanism shownin Figure 1.

A sectional machine for operating on continuous strip material is thereillustrated, and, by way of example, comprises a roller leveler Illwhich constitutes a driving section. The details of the roller levelerform no part of the present invention, it being understood that manyother ymechanisms'for operating on strip stock and at the same timemoving it longitudinally from right to left could equally well form thedriving section of the machine. l

A supply reel is indicated at `il. comprising a coil of strip I4 which,as disclosed, is partly unwound so that a fiat section of strip I6extends through the driving section i0 to a take-up reel Il where thestrip is again reeled into a coil 20. The roller leveler i0 has a'driveshaft 22 which motor 28. The latter may be of the variable'dis'-placement type provided with a manual control wheel 28 for adjusting thedisplacement to conseen that the power required to drive the take-upk 40tr01 the Speed of the leveler l0.

reel is substantially the same as the amount of power generated by thesupply reel neglecting losses. v V- It is an object of the presentinvention to/rovide an improved hydraulic power transmission systemwherein the drive at the take-up reel is so connected with the powerabsorbing means at the supply reel as to transfer this energyeiliciently fromone reel to the other with provisions for supplying anyadditional energy required to make up losses.

A further object is to provide a power transmission of this characterwherein'the reels may be operated at different values of tensionin theFor the purpose of supplying fluid to operate the motor 26 there isprovided a double set of pumps 30 and 32 driven by an electric motor 34and withdrawing oil from a tank 36 through suc- 5 tion conduits 38 and40- and delivering the same through delivery conduits 40 and 42. 'I'helatter include check valves 46 and 48 through which uid is delivered toa single supply conduit 50 vhaving the customary relief valve 52 thereinfor bypassing oil to the tank through a conduit 54 whenever the pressurein delivery line 50 exceeds a predetermined value. i

The supply conduit 50 extends to a port 56 of a manually-controlledstop-go valve 58, the ports strip while still transferring whateverpower is 55 60, 62 and 64 of which are connected to the tank viceregulates.

|18 and conduit |38 and thus provides pressure relief protection to theoutput side of unit |34 whenever valve |42 is in the center position;For the purpose of initially filling the system with oil, a conduit |86having a check valve |88 Vconnectsbetween conduit |58 and conduit |32.

Referring now to Figure 2, there is illustrated a pressure regulatorparticularly adapted for use with 'the present invention although itwill be understood that other types of pressure regulators may be usedat |28 and |50. The regulator disclosed comprises a block |96 having acylinder bore 98 formed therein in which is slidable a piston 200. Thelatter has a stem 202 to which is connected the swinging yoke of thepumpor motor unit to which the regulator is attached. 'I'he piston 200 isbiased tothe right by a relatively light spring 204 the tension ofwhich, however, does not determine the pressure to which the de- A limitstop 206 is adjustably mounted by means of a threaded stem 208 in an endcap 2|0 which closes the lefthand end of cylinder bore |98. Aspringguide pin 2|2 is also carried by the stem 208. The limit stop 206serves to determine the minimum displacement position in the regulator|28 and the maximum displacement position in the regulator |50. Acircumferential grove 2|4 is formed near the lefthand end of cylinderbore |98 to intersect a passage 2|6 communicating with the interior ofthe casing of the pump or motor unit. This groove is blocked oi by thepiston 200 as the latter approaches the lefthand end of its strokesothat thereafter communication between the pump casing and the lefthandend of cylinder bore |98 is through needle valve ZIB, thus cushioningthe movement of piston 200 at the lefthand end of its stroke. Therighthand end of cylinder bore' |98 is in restricted communication withthe interior of the pump casing through a passage 220., It is also incommunication with the discharge port of a relief valve 222 through 'apassage 224. The relief valve 222 operates similarly to that disclosedin the patent to Harry F, Vickers, No. 2,043,453, and is pilotcontrolled by means of a small pilot relief valve 228 which exhausts totank 36 through a passage 228 leading to the groove 2 I4 and passage2|6. 'I'he pressure at which valve 222 opens is governed by the springadjustment of valve 226'. The pressure connections 230 and 23| of reliefvvalve 222 connect respectively with the conduit |32 leading from pump|26 or with conduit |44 leading to motor |46. The interiors of thecasings of the three units |26, |46, and |34 are all drained to the tankby a drainage network 232.

In operation, the parts are shown in idle position with` the drivesection circuit bypassed but with the reel coupling circuit in conditionfor operation whenever the driving section I0 is started. During idleposition the delivery of pumps 30 and 32 is bypassed to tank, aspreviously described, so long as electricmotor 34 operates, while thedelivery of pumps 12 and II6 is bypassed to tank through theirrespective relief valves 18 and |22.

y When it is desired to start the entire apparatus the valve 58 may beshifted to the right toconnect ports 68 and 66- thus causing motor 26 towound from coil I4 due to the gradual decrease in the diameter thereof.

Unit |34 is also driven at a xed speed determined by the speed ofdriving section I0, and

` since unit |34 is of xed displacement, it controls Y the rate atwhich'uid can pass from pump orifice 220, the piston 200 is under aconstant tendency to move to the right and increase the stroke of pump|26. `The instant that such stroke tends to increase beyond the valuenecessary to supply the quantity which' unit |34 takes, the

y pressure in conduit |32 will immediately build up and open reliefvalve 222 thus admitting oil to the righthand end of cylinder |98 at afasterrate than it can escape through the orifice 220. Ac-

cordingly, the piston 200 will be moved back to the left, thusdecreasing the stroke of pump |26 and counteracting the tendency forthe-pressure in conduit |32 to rise.

In actual operation the parts will come to a steady condition inwhichthe relief `valve 222 is cracked open sumciently to pass oil intocylinder |98 at a slightly higher rate Athan it passes out of cylinder|98 through orice 220. Thus the piston 200 will move to the left slowlyat a speed proportional to the gradual decrease in diameter of coil I4.In this manner the volumetric delivery rate of pump ,|26 is maintainedconstant I during the gradually increasing speed thereof.

The oil discharged from unit |34 iiows through conduit |38, ports |40and |43 and conduit |44 to the inlet of uid motor |46. The quantityflowing through this path is also constant due to the constant speed ofdisplacement of unit |34. Accordingly, pressure regulator |50 will actto increase the stroke of motor |46 as is necessary to decrease thespeed of reel I8 as the diameter of coil 20 increases. The speed of reelI8 can never exceed that where the linear speed of the strip is equal tothe linear speed of the strip through driving section I0 since to do sowould "stretch, and eventually-rupture, the strip. Accordingly, anytendency for motor |46 to drive the' reel faster than this speed causesan increase in pressure in line |44 which.reacts on the pressureregulator |50 to increase the stroke of motor |46 and thereby decreasethe speed of reel I8 restoring the original condition.

In actual operation the piston 200 and pressure regulator |50 will alsomove slowly -to the left to gradually swing yoke |48 at a speedproportional to the gradual increase in diameter of coil 20. Oildischarged from motor |46 returns directly to the inlet of pump |26.This path is through conduit |52, ports |54 and |56, conduit |58 ancicheck valve |60. I

It will be noted that under these conditions of operation the speed ofthe reels I2 and I8 is controlied automatically in such a way that aconstant tension isv maintained in the strip between the reels and thedriving unit l0. This value of tension moreoveris not necessarily thesame at the right and lefthand sides of the driving section |0. 4Iheoperation o f a reel at constant strip tension or constant linear speedrequires constant horsepower operation at the reel shaft. This is .4 a YI vvvevident from the fact that'the torque Aon lthe reel driving sectionlo by the imit in shalt, being the product lof striptension and coildiameter. varies directly with the diameter of the coil, while theangular speed-being the quotient of strip speed and coil diameter.varies inversely with :t'hecoil diameter. -Since the horsepower at .theshait` is' the product of torque and speed, Athe factor of reel diameterdisappears asta factor aifecting horsepower. Ac-

cordingly, since the constant ytension reel produces (at the supplyreel) vor requires (at the vtake-up reel) a constant horsepower, itfollows that any hydraulic drive which requires or produces constanthorsepower will automatically and inherently cause constant tensionoperation at the reel, assuming, of course, that the drive provides bothvariable speed and variable torque.

Hydraulic horsepower being the product oi' rate unit 'I2C must operateat constant horsepower because unit |24 maintains a constant rate of owthrough unit |25. while the regulator |28 maintains a constant pressureof operation. Likewise at motor |46 a constant horsepower is alwaysproduced because of the constantl rate of now determined by unit |34 andthe constant operating pressure determined by regulator |50.

It should be noted, however; that |46 unless both pressure regulatorsare set .to operate at`the same pressure. lWhen they are thus set, equaltension will be maintained in the a motor.

lDuringsettingupopex'atio'ns'itisnecessaryto be able to turn the reel i2without operating the v reel coupling circuit, and for this 'purpose thecontrol valve ||l may be shifted to direct pilot Also 'it isoccasionally desirable to reverse the rotation of the reel Il forattaching the end of a new strip, and forthis= purpose'valve |42 may beshiftedto its extreme right-hand position t0 re- -verse the direction of-iiow through motor |48.

While the form of embodiment of the invention as herein disclosedconstitutes a preferred form,

A it is to be understood that other forms might be Vof 4ilow andoperating pressure, fit follows thatl the horsee power at unit I2( isnot identical to that at unit strip on both sides o the drive sectionil, and v the unit m win-operate et zero pressure dinerential, thusneither absorbing nor giving out power `from.,or to the driving sectionI0. 'I'he only function which the unit |34 4performs under' 'theseconditions is a sort of synchronizing function to -prevent huntingcausedby momentary uctua adopted, all coming within the scope of theclaims which follow.

What is claimed is'as follows:

1. In a sectional machine for operating on strip material thecombination o f a driving section having means for ensaging the stripand moving it longitudinally, power means for driving the drivingsection at a controlled speed, a supply reel section from which the.strip is unreeled by the pull'of the driving section, and` means forcontrolling-'the tension of the strip between said sections comprising avariable displacement pump mechanically coupled to the reel section inpredetermined speed ratio. a ehydraulic motor mechanically coupled tothe driving seciion in predetermined speed ratio, a series hydraulic Icircuit connecting the pump to deliver all its iiuid outputto the motor,and means responsive to an increase in pressure in said circuit forreducing the pump displacement to maintain said tions in operating'conditions'atthe'pressure regulators |28 and IM.

If the pressure regulator |2l is set for a liigherpressure than'pressure regulator lit, Ithen the power produced at reel i2 inexcessiof'that required at reel 'il is returned to the driving unit Itby unit ,|34 acting as a motor operating at the pressure diiferentialbetween unit'l28` and-|50.

-Conversely, should the reel- I2 produce less power than required tooperate reel l2 at a given adjustment of the pressure regulators, 'theunit |34 will make upthe deficiency by transferring power from drivingunit III to the reel I3. It isunder-` f stood, of course, that the abovediscussion has neglected losses in thehydraulic circuit and invv themechanical parts of the reel as well as the hysteresis losses in thebending of the sheet material.

Undercertain conditions of operation it is sometimes desired to operatethe strip handling device without recoiling the material after it haslllto ports |56 an'd |50 where it ilows to the conduit |58. It will beseen that under vthese conditions the entire quantity of power generatedat the reel l2, neglecting losses. is returned to the pressuresubstantially constant. i..

2. Inra sectional' machine for operating on `strip material the'combination of a driving section having means for engaging the strip andmoving it longitudinally, power means for driving the driving section ata controlled speed, a supply reel section from which the strip isunreeledI by the pull of the driving section, and means for controllingthe tension of the strip vbetween said sections comprising a variabledisplacement pump mechanically coupled' to the :reel section inpredetermined speed ratio, a nxed displacement hydraulic motormechanically. coupled to. the

driving section in predetermined speed ratio, a series hydraulic circuitconnecting the pump to deliver all its iiuid output'to the motor, and

means responsive to an increase in pressure in said circuit for reducingthe pump displacement to maintain said pressure substantially constant.

3. In a sectional-machine for'operating on stripmaterial the combinationof a driving section having means for engaging the strip and moving itlongitudinally, power means for driving the driving section at acontrolled speed, a supply reel section from which the strip is unreeledfrom a progressively decreasing diameter by the pull of the drivingsection, and means for'controlling the tension of' the strip betweensaid sections com prising a variable speed ratio hydraulic powertransmission system connected to be driven by the supply reel sectionand to drive the driving section, and means responsive to operatingpressure in said transmission for controlling the speed ratio of saidtransmission.

4. In a scctionalmachine for operating on strip material the combinationof a driving section having means for engaging the strip and moving itlongitudinally, power means for driving the driving section at acontrolled speed. a supply reel section from which the strip is unreeledfrom a progressively decreasing diameter by the pull of the drivingsection, and means for controlling the tension of the strip between saidsections comprising a variable speed ratio hydraulic power transmissionsystem -connected to be driven by the supply reel section and to drivethe driving section and comprising a pair of iluid pressure energytranslating devices, one of which is of the variable displacement type,and pressure responsive means for regulating the displacement of saidone device.

5. In a sectional machine for operating on strip material thecombination of a driving section having means 'for engaging the stripand moving it longitudinally, power means for driving the drivingsection at a controlled speed, a supply reel section from which thestrip is unreeled by the pull of the driving section, a take-up reelsection onto which the strip is reeled after leaving the drivingsection, and means for controlling the tension of the strip between saidthree sections comprising a variable displacement pump unit coupled tothe supply reel section and having means for controlling itsdisplacement to mtaintain a substantially constant delivery pressure, avariable displacement motor unit coupled with the take-up reel sectionand having means 'for controlling its displacement to maintain asubstantially constant inlet pressure, and means mechanically coupledwith the driving section and hydraulically connected with said units formetering the quantity of uid passing through each of said variabledisplacement units in predetermined ratio to the longitudinal movement'of the strip through the driving section.

6. In a sectional machine for operating on strip material thecombination of a driving section having means for engaging the strip andmoving it longitudinally, power means for driving the driving secizlonat a controlled speed, a supply reel section from which the strip isunreeled by the pull of the driving section, a take-up reel section ontowhich the strip is `reeled after leaving the driving section, and meansfor controlling the` tension of the strip between said three sectionscomprising a variable displacement pump unit coupled to the supply reelsection and having means for controlling its displacement to maintain asubstantially constant delivery pressure, a variable displacement motorunit coupled with `the take-up reel section and having means forcontrolling its displacement to maintain a sub- 'f units beingadjustable to regulate to diierent pressures whereby the strip tensionon one side of the driving section may be varied relative to that on theother side thereof.

7. In a sectional machine for operating on strip material thecombination of a driving section having means for engaging the strip andmoving it longitudinally, power means for driving the driving section ata controlled speed, a

supply reel section from which the strip is unreeled by the pull of thedriving section, a takeup reel section onto which the strip is reeledafter leaving the driving section, and means for controlling the tensionof the strip between said three sections comprising a variabledisplacement pump unit coupled to the supply reel section and havingmeans for controlling its displacement to maintain -a substantiallyconstant delivery pressure, a variable displacement motor unit coupledwith the take-up reel section and having means for controlling itsdisplacement to maintain a-substantially constant linlet pressure, andmeans including a xed displacement iluid pressure energy translatingdevice mechanically coupled with the driving section and hydraulicallyconnected with said units for metering the quantity of fluid passingthrough each of said variable displacement units in predetermined ratioto the longitudinal movement of the strip through the driving section. Y

8. In a sectional machine foroperating on strip material the combinationof a driving section having means for engaging the strip and moving itstrip material the combination of a Ydriving sec- A tain a substantiallyconstant delivery pressure, a

variable displacement motor unit coupled with the take-up reel sectionand having means for controlling its displacement to maintain asubstantially constant inlet pressure, and means includ'- ing a xeddisplacement fluid pressure energy translating device mechanicallycoupled with the driving section and hydraulically connected in a seriescircuit with both said units for metering the quantity of fluid passingthrough each of said .variable displacement units in predetermined ratioto the longitudinal movement of the strip through the'driving section.

9. A strip material handling device comprising y l a supply reel fromwhich the strip is to be unwound and a take-up reel onto which the samestrip is to be wound, a pair of constantA pressure, variable volume,hydraulic displacement devices, one connected in driving relation toeach reel, a

constant volume, variable pressure, hydraulic displacement device, meansfor driving the lastmentioned device at a controlled speed, and uidsupply and return conduits connecting said three devices in a seriescircuit. e

10. In a sectional machine for operating on tion having means forengaging the strip and moving it longitudinally, power means for drivingthe driving section at a controlled speed, a supply reel `section fromwhich the strip is unreeled by the pull of the driving section, atake-up reel section onto which the strip is reeled after leaving thedriving section, and means for controlling the tension of the stripbetween said three sections comprising a variable displacement pump unitcoupled to the supplyl reel section and having means for controlling itsdisplacement to maintain a substantially constant delivery pressure, avariable displacement motor unit coupled with the take-up reel sectionland having means for controlling its displacement to maintain asubstantially constant inlet pressure, means mechanically coupled withthe driving section and hydraulically connected with said units formetering the quantity of fluid passing through'eachA of said variabledisplacement units in predetermined ratio to the longitudinal movementof the 6 y strikthoushizhcdrivinizsection..niimennlin#Acludingi.vulveselectivelyshiiiumbletociismm-vnectoneofsaidunitstromnidmetermzmelnl -11.. Astripmnteridhandlin'zdevicecomln'isinz asupplyxeeltromwhichthextripistobeuniwoundandatoke-upreeiontowhichthenmesisx'ipis1:0hevound,ammiro!constanizprenure.Avariablevolumghydrsulicdisplacementdevices,oneconnechedindrivingrelstionfoeochnel.:

constant volume. -vu'iable pressure, hydraulic 10'theremniningtwodevicesinseri mms T. mRRmGToN. Jem RoniNSON.

